Array substrate and fabrication method thereof, and display device

ABSTRACT

Embodiments of the disclosure disclose an array substrate and a fabrication method thereof, and a display device. The fabrication method of the array substrate comprises: forming a thin film transistor; forming a passivation layer covering the thin film transistor, the passivation layer having a via hole and the via hole exposing at least a portion of a drain electrode of the thin film transistor; forming a via-hole conductive layer, the via-hole conductive layer covering the portion of the drain electrode exposed at the via hole and connected to the drain electrode; treating the via-hole conductive layer, so that a reflectivity of the via-hole conductive layer is lower than a reflectivity of the drain electrode; and forming a pixel electrode, the pixel electrode being connected with the drain electrode through the via-hole conductive layer.

TECHNICAL FIELD

Embodiments of the disclosure relate to an array substrate and afabrication method thereof, and a display device.

BACKGROUND

A thin film transistor liquid crystal display device mainly comprises anarray substrate, a color filter substrate, and a liquid crystal layersandwiched between the array substrate and the color filter substrate.The array substrate comprises gate lines, data lines and a plurality ofpixel regions by intersecting the gate lines and the data lines witheach other. Within each pixel region, there are formed a thin filmtransistor and a pixel electrode. The pixel electrode is connected to adrain electrode of the thin film transistor through a via hole formed ina passivation layer covering the thin film transistor. A color filterlayer formed of color filters of red, green and blue (R, G, B) and ablack matrix are formed on the color filter substrate. The black matrixis disposed to correspond to the thin film transistor to prevent lightleakage.

In a practical process, there is often a deviation when the arraysubstrate and the color filter substrate are bonded with each other, andthus it is necessary to increase a width of the black matrix in order toavoid light leakage caused by such deviation. However, increase of thewidth of the black matrix will reduce an aperture ratio of the pixelregion and degrade the display quality. In order to solve the aboveproblem, a Color filter On Array (COA) technology in which the colorfilter layer and the black matrix are directly formed on the arraysubstrate emerges. In the COA technology, the color filter layer and theblack matrix are formed on the array substrate together with the thinfilm transistor, which not only can improve the aperture ratio andbrightness of the display device, but also can avoid various problemscaused by forming the color filter layer and the thin film transistor ondifferent substrates.

However, in the COA technology in which the black matrix is formed onthe array substrate, although the black matrix shields the thin filmtransistor and the metal wires (e.g., the gate lines and the datalines), the drain electrode provided at the via hole of the passivationlayer cannot be shielded by the black matrix for the drain electrodeprovided at the via hole of the passivation layer needs to be connectedto the pixel electrode. In this case, the drain electrode at the viahole will reflect the ambient light, resulting in reduction of contrastratio and color purity of the display device, so that the display effectof the display device is seriously affected.

SUMMARY

According to embodiments of the disclosure, there is provided afabrication method of an array substrate. For example, The fabricationmethod of the array substrate comprises: forming a thin film transistor;forming a passivation layer covering the thin film transistor, thepassivation layer having a via hole and the via hole exposing at least aportion of a drain electrode of the thin film transistor; forming avia-hole conductive layer, the via-hole conductive layer covering theportion of the drain electrode exposed at the via hole and connected tothe drain electrode; treating the via-hole conductive layer, so that areflectivity of the via-hole conductive layer is lower than areflectivity of the drain electrode; and forming a pixel electrode, thepixel electrode being connected with the drain electrode through thevia-hole conductive layer.

For example, the fabrication method of the array substrate furthercomprises: forming a common electrode. The via-hole conductive layer andthe common electrode are formed simultaneously, and the via-holeconductive layer and the common electrode are disconnected from eachother.

For example, the fabrication method of the array substrate furthercomprises: forming an inter-electrode insulating layer on the via-holeconductive layer and the common electrode; performing a patterningprocess on the inter-electrode insulating layer, so as to expose thevia-hole conductive layer; and treating the via-hole conductive layer,so that the reflectivity of the via-hole conductive layer is lower thanthe reflectivity of the drain electrode.

For example, the fabrication method of the array substrate furthercomprises: forming the pixel electrode on the inter-electrode insulatinglayer.

For example, the via-hole conductive layer is formed integrally with thepixel electrode.

For example, the fabrication method of the array substrate furthercomprises: forming a pixel electrode layer; coating a photoresist on thepixel electrode layer, exposing and developing the photoresist by usinga dual-tone mask to form a photoresist fully-reserved region, aphotoresist partially-reserved region and a photoresist fully-removedregion, the photoresist fully-reserved region corresponding to a regionwhere the pixel electrode is to be formed, the photoresistpartially-reserved region corresponding to a region where the via-holeconductive layer is to be formed, and the photoresist fully-removedregion corresponding to other region; removing the pixel electrode layerin the photoresist fully-removed region by etching; removing thephotoresist in the photoresist partially-reserved region by ashing toform the via-hole conductive layer; treating the via-hole conductivelayer with remaining photoresist as a mask, so that the reflectivity ofthe via-hole conductive layer is lower than the reflectivity of thedrain electrode; and removing the remaining photoresist to obtain thepixel electrode.

For example, the fabrication method of the array substrate furthercomprises: forming a pixel electrode layer; performing a patterningprocess on the pixel electrode layer by using a first single-tone maskto form the pixel electrode and the via-hole conductive layer; andtreating the via-hole conductive layer by using a second single-tonemask, so that the reflectivity of the via-hole conductive layer is lowerthan the reflectivity of the drain electrode.

For example, the treating the via-hole conductive layer comprises:treating the via-hole conductive layer by a hydrogen treatment process.

For example, hydrogen plasma is used in the hydrogen treatment process.

For example, the fabrication method of the array substrate furthercomprises: forming a black matrix and a color filter layer. The blackmatrix is formed to correspond to the thin film transistor, and thecolor filter layer is formed to correspond to the pixel electrode.

For example, the fabrication method of the array substrate furthercomprises: forming an organic insulating layer. The organic insulatinglayer is formed between a layer where the pixel electrode is providedand a layer where the drain electrode is provided.

For example, the fabrication method of the array substrate furthercomprises: forming a spacer. The spacer is provided in a topmost layerof the array substrate.

According to embodiments of the disclosure, there is provided an arraysubstrate. For example, the array substrate may comprise: a thin filmtransistor; a passivation layer, covering the thin film transistor, thepassivation layer having a via hole and the via hole exposing at least aportion of a drain electrode of the thin film transistor; a via-holeconductive layer, covering the portion of the drain electrode exposed atthe via hole and connected to the drain electrode, and a reflectivity ofthe via-hole conductive layer being lower than a reflectivity of thedrain electrode; and a pixel electrode, connected with the drainelectrode through the via-hole conductive layer.

For example, the array substrate further comprises a common electrode.The via-hole conductive layer and the common electrode layer aredisposed in a same layer, and the via-hole conductive layer and thecommon electrode are disconnected from each other.

For example, the via-hole conductive layer and the pixel electrode aredisposed in a same layer, and the via-hole conductive layer and thepixel electrode are connected with each other.

For example, the array substrate further comprises a black matrix and acolor filter layer. The black matrix corresponds to the thin filmtransistor, and the color filter layer corresponds to the pixelelectrode.

For example, the array substrate further comprises an organic insulatinglayer. The organic insulating layer is provided between a layer wherethe pixel electrode is provided and a layer where the drain electrode isprovided.

For example, the array substrate further comprises a spacer. The spaceris provided in a topmost layer of the array substrate.

According to embodiments of the disclosure, there is provided a displaydevice. For example, the display device comprises the array substrate asdescribed above.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to clearly illustrate the technical solution of the embodimentsof the disclosure, the drawings of the embodiments will be brieflydescribed in the following; it is obvious that the described drawingsare only related to some embodiments of the disclosure and thus are notlimitative of the disclosure.

FIG. 1 is a schematic diagram of forming a thin film transistor in afabrication method of an array substrate according to embodiments of thedisclosure;

FIG. 2 is a schematic diagram of forming a passivation layer and a viahole in the fabrication method of the array substrate according to theembodiments of the disclosure;

FIG. 3 is a schematic diagram of forming a black matrix in thefabrication method of the array substrate according to the embodimentsof the disclosure;

FIG. 4 is a schematic diagram of forming a color filter layer in thefabrication method of the array substrate according to the embodimentsof the disclosure;

FIG. 5 is a schematic diagram of forming a common electrode and avia-hole conductive layer in the fabrication method of the arraysubstrate according to the embodiments of the disclosure;

FIG. 6 is a schematic diagram of forming an inter-electrode insulatinglayer in the fabrication method of the array substrate according to theembodiments of the disclosure;

FIG. 7 is a schematic diagram of treating the via-hole conductive layerto reduce reflectivity thereof in the fabrication method of the arraysubstrate according to the embodiments of the disclosure;

FIG. 8 is a schematic diagram of forming a pixel electrode in thefabrication method of the array substrate according to the embodimentsof the disclosure;

FIG. 9 is a schematic diagram of forming a spacer in the fabricationmethod of the array substrate according to the embodiments of thedisclosure;

FIG. 10 is a schematic diagram of forming an organic insulating layer inthe fabrication method of the array substrate according to theembodiments of the disclosure; and

FIG. 11 is a schematic diagram of forming the pixel electrode and thevia-hole conductive layer in the fabrication method of the arraysubstrate according to the embodiments of the disclosure.

DESCRIPTION OF THE EMBODIMENTS

In order to make objects, technical details and advantages of theembodiments of the disclosure apparent, the technical solutions of theembodiment will be described in a clearly and fully understandable wayin connection with the drawings related to the embodiments of thedisclosure. It is obvious that the described embodiments are just a partbut not all of the embodiments of the disclosure. Based on the describedembodiments herein, those skilled in the art can obtain otherembodiment(s), without any inventive work, which should be within thescope of the disclosure.

Unless otherwise defined, all the technical and scientific terms usedherein have the same meanings as commonly understood by one of ordinaryskill in the art to which the disclosure belongs. The terms “first,”“second,” etc., which are used in the description and the claims of thedisclosure, are not intended to indicate any sequence, amount orimportance, but distinguish various components. Also, the terms such as“a,” “an,” etc., are not intended to limit the amount, but indicate theexistence of at least one. The terms “comprise,” “comprising,”“include,” “including,” etc., are intended to specify that the elementsor the objects stated before these terms encompass the elements or theobjects and equivalents thereof listed after these terms, but do notpreclude the other elements or objects. “On,” “under,” “right,” “left”and the like are only used to indicate relative position relationship,and when the position of the object which is described is changed, therelative position relationship may be changed accordingly.

According to embodiments of the disclosure, there is provided afabrication method of an array substrate. The fabrication method of thearray substrate comprises: forming a thin film transistor; forming apassivation layer covering the thin film transistor, the passivationlayer having a via hole and the via hole exposing at least a portion ofa drain electrode of the thin film transistor; forming a via-holeconductive layer, the via-hole conductive layer covering the portion ofthe drain electrode exposed at the via hole and connected to the drainelectrode; treating the via-hole conductive layer, so that areflectivity of the via-hole conductive layer is lower than areflectivity of the drain electrode; and forming a pixel electrode, thepixel electrode being connected with the drain electrode through thevia-hole conductive layer.

In the fabrication method of the array substrate according to theembodiments of the disclosure, since the via-hole conductive layercovers the portion of the drain electrode exposed at the via hole andthe reflectivity of the via-hole conductive layer after being treated islower than the reflectivity of the drain electrode, light reflection ofthe drain electrode can be avoided and display quality of the displaydevice can be improved.

In the fabrication method of the array substrate according to theembodiments of the disclosure, the via-hole conductive layer may beformed by an individual process and the via-hole conductive layer may betreated by another individual process to reduce the reflectivitythereof. However, in order to simplify the fabrication process andreduce fabrication cost, it is desirable that the step of forming thevia-hole conductive layer and the step of treating the via-holeconductive layer to reduce the reflectivity thereof are performedsimultaneously with the steps of forming other components of the arraysubstrate. For example, in one case: the via-hole conductive layer andthe common electrode are formed simultaneously; and in the other case:the via-hole conductive layer and the pixel electrode are formedsimultaneously. Here, as an example, the fabrication method of the arraysubstrate in the above-described two cases will be described in detailin conjunction with the accompanying drawings.

[The Via-Hole Conductive Layer and the Common Electrode are FormedSimultaneously]

FIG. 1 to FIG. 10 are schematic diagrams illustrating the fabricationmethod of the array substrate according to embodiments of thedisclosure. As shown in FIG. 1 to FIG. 10, the fabrication method of thearray substrate according to the embodiments of the disclosure comprisesthe following steps.

Firstly, a thin film transistor is formed on a base substrate 1, asshown in FIG. 1. The thin film transistor is of a bottom gate type or atop gate type. As an example, the thin film transistor of bottom gatetype is shown in the drawings.

The thin film transistor comprises a gate electrode 2, a gate insulatinglayer 5, an active layer 6, a source electrode 7 and a drain electrode8. At the time that the gate electrode 2 is formed, gate lines (notshown), common electrode lines 3 and an interface pad 4 may be formedsimultaneously. At the time that the source electrode 7 and the drainelectrode 8 are formed, data lines (not shown) may be formedsimultaneously. The gate lines and the data lines intersect with eachother to define a plurality of pixel units in the form of a matrix. Inthe drawings, as an example, only one pixel unit is shown, but otherpixel units may be formed similarly.

Next, a passivation layer 9 is formed, and a patterning process isperformed on the passivation layer 9 to form a via hole 10 in thepassivation layer 9, as shown in FIG. 2. The via hole 10 is provided atthe drain electrode 8 of the thin film transistor, to expose at least aportion of the drain electrode 8. At the time that the via hole 10 isformed, an additional via hole 10′ may be formed simultaneously. Theadditional via hole 10′ is provided at the common electrode line 3 andextends through the gate insulating layer 5 to expose a portion of thecommon electrode line 3.

Next, a black matrix 11 and a color filter layer 12 are formed, as shownin FIG. 3 and FIG. 4. The black matrix 11 is formed to correspond to thethin film transistor, and the color filter layer 12 is formed tocorrespond to the pixel electrode which is formed subsequently.

For example, the array substrate comprises a red pixel unit, a greenpixel unit and a blue pixel unit; and accordingly, the color filterlayer 12 comprises a red color filter provided in the red pixel unit, agreen color filter provided in the green pixel unit, and a blue colorfilter provided in the blue pixel unit. The red color filter, the greencolor filter and the blue color filter are formed by differentpatterning processes.

Next, a common electrode 13 and a via-hole conductive layer 14 areformed, as shown in FIG. 5. Specifically, first of all, a commonelectrode layer is deposited, and then a patterning process is performedon the common electrode layer to simultaneously form the commonelectrode 13 and the via-hole conductive layer 14. The common electrode13 and the via-hole conductive layer 14 are disconnected from eachother. The common electrode 13 is connected to the common electrode line3 through the additional via hole 10′. The via-hole conductive layer 14is provided at the via hole 10. Further, the via-hole conductive layer14 covers the portion of the drain electrode 8 exposed at the via hole10 and is connected with the drain electrode 8. For example, the commonelectrode 13 and the via-hole conductive layer 14 are made oftransparent conductive oxides such as Indium Tin Oxide (ITO), IndiumZinc Oxide (IZO), tin oxide and so on.

Next, an inter-electrode insulating layer 15 is formed and a patterningprocess is performed on the inter-electrode insulating layer 15 toexpose the via-hole conductive layer 14, as shown in FIG. 6. Theinter-electrode insulating layer 15 covers the whole substrate and onlyexposes the via-hole conductive layer 14.

Next, the exposed via-hole conductive layer 14 is treated, to reduce thereflectivity thereof, as shown in FIG. 7. For example, the exposedvia-hole conductive layer 14 is treated by a hydrogen treatment process,and further, hydrogen plasma is used in the hydrogen treatment process.For example, the hydrogen treatment process is performed on the via-holeconductive layer 14 under a pressure of 40-200 mtorr for 10-300 seconds.Further, for example, the hydrogen treatment process is performed on thevia-hole conductive layer 14 under a pressure of 60 mtorr for 60seconds. As described above, the via-hole conductive layer for exampleis made of ITO, which typically contains 90% of In₂O₃ and 10% of SnO₂;upon the hydrogen treatment process is performed, hydrogen reduces Sn inthe SnO₂ and the reduced Sn precipitates to form black spots on thesurface of the ITO, so that the surface of the via-hole conductive layer14 becomes hazing and the reflectivity of the via-hole conductive layer14 is significantly lowered and is lower than the reflectivity of thedrain electrode 8 made of metal. Since the via-hole conductive layer 14covers the portion of the drain electrode 8 exposed at the via hole 10and the reflectivity of the via-hole conductive layer 14 after beingtreated is lower than the reflectivity of the drain electrode 8, itavoids the case that the drain electrode 8 reflects the ambient light,thus the display quality of the display device is improved.

In addition, as shown in FIG. 7, in the above-described step of treatingthe exposed via-hole conductive layer 14 to reduce the reflectivitythereof, the inter-electrode insulating layer 15 protects the wholesubstrate from being affected, so it is unnecessary to arrange adedicated mask to protect the substrate in this step. Thus, thefabrication process can be further simplified and the fabrication costcan be further reduced.

Finally, a pixel electrode 16 is formed, as shown in FIG. 8. Forexample, the pixel electrode 16 is made of transparent conductive oxidessuch as Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), tin oxide andso on, and the pixel electrode 16 is a slit electrode having a pluralityof slits. The pixel electrode 16 is connected to the drain electrode 8of the thin film transistor through the via-hole conductive layer 14.

[The Via-Hole Conductive Layer and the Pixel Electrode are FormedSimultaneously]

Next, the case that the via-hole conductive layer and the pixelelectrode are formed simultaneously will be described in detail withreference to FIG. 11. In the following description, only featuresdifferent from those in the case where the via-hole conductive layer andthe common electrode are formed simultaneously will be described, andthe same features will not be repeated.

In the fabrication method of the array substrate according to theembodiments of the disclosure, the via-hole conductive layer 14 and thepixel electrode 16 are formed simultaneously and connected to eachother. As shown in FIG. 11, the via-hole conductive layer 14 and thepixel electrode 16 are integrally formed.

For example, in the process of forming the via-hole conductive layer 14and the pixel electrode 16 and treating the via-hole conductive layer 14to reduce the reflectivity thereof, a dual-tone mask (e.g., a gray-tonemask or a half-tone mask) is used. Firstly, the pixel electrode layer isformed; then the photoresist is coated on the pixel electrode layer, thephotoresist is exposed and developed by using the dual-tone mask to forma photoresist fully-reserved region, a photoresist partially-reservedregion and a photoresist fully-removed region, the photoresistfully-reserved region corresponds to a region where the pixel electrodeis to be formed, the photoresist partially-reserved region correspondsto a region where the via-hole conductive layer is to be formed, and thephotoresist fully-removed region corresponds to other region; the pixelelectrode layer of the photoresist fully-removed region is removed byetching; the photoresist in the photoresist partially-reserved region isremoved by ashing to form the via-hole conductive layer; with theremaining photoresist as the mask, the via-hole conductive layer istreated so that the reflectivity of the via-hole conductive layer islower than the reflectivity of the drain electrode; and the remainingphotoresist is removed to obtain the pixel electrode. Sine in theprocess of forming the via-hole conductive layer 14 and the pixelelectrode 16 and treating the via-hole conductive layer 14 to reduce thereflectivity thereof, only one dual-tone mask is used, the fabricationprocess can be further simplified and the fabrication cost can befurther reduced.

For example, the pixel electrode 16 and the via-hole conductive layer 14are made of transparent conductive oxides such as Indium Tin Oxide(ITO), Indium Zinc Oxide (IZO), tin oxide and so on.

For example, the via-hole conductive layer 14 is treated by a hydrogentreatment process, and further, hydrogen plasma is used in the hydrogentreatment process. For example, the hydrogen treatment process isperformed on the via-hole conductive layer 14 under a pressure of 40-200mtorr for 10-300 seconds. Further, for example, the hydrogen treatmentprocess is performed on the via-hole conductive layer 14 under apressure of 60 mtorr for 60 seconds. As described above, the via-holeconductive layer for example is made of ITO, which typically contains90% of In₂O₃ and 10% of SnO₂; upon the hydrogen treatment process isperformed, hydrogen reduces Sn in the SnO₂ and the reduced Snprecipitates to form black spots on the surface of the ITO, so that thesurface of the via-hole conductive layer 14 becomes hazing and thereflectivity of the via-hole conductive layer 14 is significantlylowered and is lower than the reflectivity of the drain electrode 8 madeof metal. Since the via-hole conductive layer 14 covers the portion ofthe drain electrode 8 exposed at the via hole 10 and the reflectivity ofthe via-hole conductive layer 14 after being treated is lower than thereflectivity of the drain electrode 8, it avoids the case that the drainelectrode 8 reflects the ambient light, thus the display quality of thedisplay device is improved.

Of course, in the process of forming the via-hole conductive layer 14and the pixel electrode 16 and treating the via-hole conductive layer 14to reduce the reflectivity thereof, two single-tone masks are used.Firstly, the pixel electrode layer is formed; then a patterning processis performed on the pixel electrode layer by using a first single-tonemask to obtain the pixel electrode and the via-hole conductive layerthat are formed integrally; finally, the via-hole conductive layer 14 istreated by using a second single-tone mask, so that the reflectivitythereof is lower than the reflectivity of the drain electrode.

For example, the treating the via-hole conductive layer 14 by using thesecond single-tone mask so that the reflectivity thereof is lower thanthe reflectivity of the drain electrode comprises: coating thephotoresist to cover the whole substrate; exposing and developing thephotoresist by using the second single-tone mask to form the photoresistfully-removed region and the photoresist fully-reserved region, thephotoresist fully-removed region corresponding to the via-holeconductive layer, and the photoresist fully-reserved regioncorresponding to other region; treating the via-hole conductive layer ofthe photoresist fully-removed region so that the reflectivity thereof islower than the reflectivity of the drain electrode; and removing thephotoresist of the photoresist fully-reserved region.

It should be noted that, although FIG. 11 shows the array substrate ofthe display device in an ADS mode, the technical solution that thevia-hole conductive layer and the pixel electrode are formedsimultaneously is also applicable to the array substrate of the displaydevice in a VA mode, an IPS mode and the like.

It should be noted that, in the fabrication method of the arraysubstrate according to the embodiments of the disclosure, in addition tothe above-described steps, a spacer 17 may be further formed, as shownin FIG. 9. After the array substrate is bonded with an oppositesubstrate, the spacer 17 is used for maintaining a cell gap between thearray substrate and the opposite substrate. For example, the spacer 17is provided in a topmost layer of the array substrate.

It should be noted that, in the fabrication method of the arraysubstrate according to the embodiments of the disclosure, in addition tothe above steps, an organic insulating layer 18 may further be formed,as shown in FIG. 10. The organic insulating layer 18 is provided betweena layer where the pixel electrode 16 is provided and a layer where thedrain electrode 8 is provided, to reduce a parasitic capacitance betweenthe layer where the pixel electrode 16 is provided and the layer wherethe drain electrode 8 is provided, for example, a parasitic capacitanceC_(pd) between the pixel electrode 16 and the data lines. For example,the organic insulating layer 18 is made of polyimide, epoxy resin andthe like.

It should be noted that, in the fabrication method of the arraysubstrate according to the embodiments of the disclosure, the basesubstrate 1, the gate electrode 2, the gate insulating layer 5, theactive layer 6, the source electrode 7 and the drain electrode 8, thepassivation layer 9, the black matrix 11, the color filter layer 12, theinter-electrode insulating layer 15 and the spacer 17 may be made of anyknown materials by any known processes, which will not be repeated here.

According to the embodiments of the disclosure, there is furtherprovided an array substrate. The array substrate comprises: a thin filmtransistor; a passivation layer, covering the thin film transistor, thepassivation layer having a via hole and the via hole exposing at least aportion of a drain electrode of the thin film transistor; a via-holeconductive layer, covering the portion of the drain electrode exposed atthe via hole and connected to the drain electrode, a reflectivity of thevia-hole conductive layer being lower than a reflectivity of the drainelectrode; and a pixel electrode, connected with the drain electrodethrough the via-hole conductive layer.

In the array substrate according to the embodiments of the disclosure,since the via-hole conductive layer covers the portion of the drainelectrode exposed at the via hole and the reflectivity of the via-holeconductive layer is lower than the reflectivity of the drain electrode,light reflection of the drain electrode can be avoided and displayquality of the display device can be improved.

According to the embodiments of the disclosure, there is furtherprovided a display device. The display device comprises the arraysubstrate according to any of the embodiments described above. Thedisplay device comprises the array substrate and an opposite substrate,the array substrate and the opposite substrate are bonded with eachother to form a liquid crystal cell in which liquid crystal material isfilled. The opposite substrate is, for example, a color filtersubstrate. In some examples, the liquid crystal display device furthercomprises a backlight unit for providing backlight for the arraysubstrate. The liquid crystal display device, for example, may beimplemented as: a liquid crystal display panel, an electronic paper, anorganic light-emitting diode (OLED) panel, a mobile phone, a tabletpersonal computer, a television, a monitor, a notebook computer, adigital photo frame, a navigator, a watch and any other products orcomponents having a display function.

Since the display device according to the embodiments of the disclosurecomprises the array substrate as described above, light reflection ofthe drain electrode can be avoided and the display quality of thedisplay device can be improved.

The foregoing embodiments merely are exemplary embodiments of thedisclosure, and not intended to define the scope of the disclosure, andthe scope of the disclosure is determined by the appended claims.

The disclosure claims priority to and contains subject matters relatedto that disclosed in Chinese Priority Patent ApplicationCN201410697709.1 filed on Nov. 26, 2014, the entire content of which ishereby incorporated by reference.

What is claimed is:
 1. A fabrication method of an array substrate, the array substrate comprising gate lines and data lines intersecting with each other to define a plurality of pixel units, the method comprising: forming a thin film transistor; forming a passivation layer covering the thin film transistor, the passivation layer having a via hole and the via hole exposing at least a portion of a drain electrode of the thin film transistor; forming a via-hole conductive layer, the via-hole conductive layer covering the portion of the drain electrode exposed at the via hole and connected to the drain electrode; treating the via-hole conductive layer, so that a reflectivity of the via-hole conductive layer is lower than a reflectivity of the drain electrode; and forming a pixel electrode, the pixel electrode being connected with the drain electrode through the via-hole conductive layer, wherein the via-hole conductive layer is provided at the via hole so that no portions of the via-hole conductive layer extent into a display region of each pixel unit.
 2. The fabrication method of the array substrate according to claim 1, further comprising: forming a common electrode, wherein the via-hole conductive layer and the common electrode are formed simultaneously, and the via-hole conductive layer and the common electrode are disconnected from each other.
 3. The fabrication method of the array substrate according to claim 2, further comprising: forming an inter-electrode insulating layer on the via-hole conductive layer and the common electrode; performing a patterning process on the inter-electrode insulating layer, so as to expose the via-hole conductive layer; and treating the via-hole conductive layer, so that the reflectivity of the via-hole conductive layer is lower than the reflectivity of the drain electrode.
 4. The fabrication method of the array substrate according to claim 3, further comprising: forming the pixel electrode on the inter-electrode insulating layer.
 5. The fabrication method of the array substrate according to claim 1, wherein the via-hole conductive layer is formed integrally with the pixel electrode.
 6. The fabrication method of the array substrate according to claim 5, further comprising: forming a pixel electrode layer; coating a photoresist on the pixel electrode layer, exposing and developing the photoresist by using a dual-tone mask to form a photoresist fully-reserved region, a photoresist partially-reserved region and a photoresist fully-removed region, the photoresist fully-reserved region corresponding to a region where the pixel electrode is to be formed, the photoresist partially-reserved region corresponding to a region where the via-hole conductive layer is to be formed, and the photoresist fully-removed region corresponding to other region; removing the pixel electrode layer in the photoresist fully-removed region by etching; removing the photoresist in the photoresist partially-reserved region by aching to form the via-hole conductive layer; treating the via-hole conductive layer with remaining photoresist as a mask, so that the reflectivity of the via-hole conductive layer is lower than the reflectivity of the drain electrode; and removing the remaining photoresist to obtain the pixel electrode.
 7. The fabrication method of the array substrate according to claim 5, further comprising: forming a pixel electrode layer; performing a patterning process on the pixel electrode layer by using a first single-tone mask to form the pixel electrode and the via-hole conductive layer; and treating the via-hole conductive layer by using a second single-tone mask, so that the reflectivity of the via-hole conductive layer is lower than the reflectivity of the drain electrode.
 8. The fabrication method of the array substrate according to claim 1, wherein the treating the via-hole conductive layer comprises: treating the via-hole conductive layer by a hydrogen treatment process.
 9. The fabrication method of the array substrate according to claim 8, wherein hydrogen plasma is used in the hydrogen treatment process.
 10. The fabrication method of the array substrate according to claim 1, further comprising: forming a black matrix and a color filter layer, wherein the black matrix is formed to correspond to the thin film transistor, and the color filter layer is formed to correspond to the pixel electrode.
 11. The fabrication method of the array substrate according to claim 1, further comprising: forming an organic insulating layer, wherein the organic insulating layer is formed between a layer where the pixel electrode is provided and a layer where the drain electrode is provided.
 12. The fabrication method of the array substrate according to claim 1, further comprising: forming a spacer, wherein the spacer is provided in a topmost layer of the array substrate.
 13. A fabrication method of an array substrate, comprising: forming a thin film transistor; forming a passivation layer covering the thin film transistor, the passivation layer having a via hole and the via hole exposing at least a portion of a drain electrode of the thin film transistor; forming a via-hole conductive layer, the via-hole conductive layer covering the portion of the drain electrode exposed at the via hole and connected to the drain electrode; treating the via-hole conductive layer, so that a reflectivity of the via-hole conductive layer is lower than a reflectivity of the drain electrode; and forming a pixel electrode, the pixel electrode being connected with the drain electrode through the via-hole conductive layer, wherein the method further comprises: forming a pixel electrode layer; coating a photoresist on the pixel electrode layer, exposing and developing the photoresist by using a dual-tone mask to form a photoresist fully-reserved region, a photoresist partially-reserved region and a photoresist fully-removed region, the photoresist fully-reserved region corresponding to a region where the pixel electrode is to be formed, the photoresist partially-reserved region corresponding to a region where the via-hole conductive layer is to be formed, and the photoresist fully-removed region corresponding to other region; removing the pixel electrode layer in the photoresist fully-removed region by etching; removing the photoresist in the photoresist partially-reserved region by ashing to form the via-hole conductive layer; treating the via-hole conductive layer with remaining photoresist as a mask, so that the reflectivity of the via-hole conductive layer is lower than the reflectivity of the drain electrode; and removing the remaining photoresist to obtain the pixel electrode.
 14. A fabrication method of an array substrate, comprising: forming a thin film transistor; forming a passivation layer covering the thin film transistor, the passivation layer having a via hole and the via hole exposing at least a portion of a drain electrode of the thin film transistor; forming a via-hole conductive layer, the via-hole conductive layer covering the portion of the drain electrode exposed at the via hole and connected to the drain electrode; treating the via-hole conductive layer, so that a reflectivity of the via-hole conductive layer is lower than a reflectivity of the drain electrode; and forming a pixel electrode, the pixel electrode being connected with the drain electrode through the via-hole conductive layer, wherein the method further comprises: forming a pixel electrode layer; performing a patterning process on the pixel electrode layer by using a first single-tone mask to form the pixel electrode and the via-hole conductive layer; and treating the via-hole conductive layer by using a second single-tone mask, so that the reflectivity of the via-hole conductive layer is lower than the reflectivity of the drain electrode. 